I will advice him to stop gambling. I will not help him at all than to buy only food for him and it will not be expensive ones but cheap ones. He should stop the addiction and start a better life. It is as simple as that.
This decision might seem cruel to a lot of people but in life hard choices must be made for the greater good...if you don't treat the situation like this the addicted gambler might just continue feeding his addictions.. Gambling addicts have a way of manipulating and gas lighting people when they don't get what they want, it's important for people to recognize this and stop falling for it.. seeking help is the first step the gambler can make
For me I don't see anything hard here to achieve, you already know that the gambler have problems of addiction so why then should you risk giving them money to go and waste away, I don't think that is a smart thing to do even if the gambler is a close family person to you, you have to deny him that money to at least limits his gambling excapeds, don't care about what anyone will say to you just do the right thing and dont give a heck about the world and their emotional blackmailing.